I saw an Oprah special last year about fertility and it was this huge uproar thing in the USA at the time - lots of media coverage. The gist of it was that fertility starts to drop at age 27 (like KeenAs said above). Its different for each woman (obviously) but it would be wrong to assume that you have until you're 35 before your fertility starts to be affected by your age. All the people on the show were saying that they felt like they were ripped off because they had missed their chance or their doctor never told them that fertility starts to drop at such a young age (talking about 27).

DH and I were very keen to be "financially stable" before we had any kids, and we actually managed to pay off our first home before we started TTC. We were lucky I guess, but during the pregnancy we decided to upgrade, so now we have a mortgage again anyway LOL!

Like the others said, there's never a right time, but when you get near it, you'll know for sure because your body will make sure you're aware of time marching on!